De-N-glycosylation Will Be the Novel Pathway for Processing of the Tumor Antigen Presented by MHC Class I

Abstract Transfection with tumor antigen RNA is one of the promising tools not only because of a possible sufficient amplification of tumor antigen RNA but also because of the absence of antigen peptides-associated MHC restriction. Several succeeded experiments about generation of CTLs using DCs transfeced in vitro transcribed (IVT) cancer specific antigen mRNA such as PSA, CEA, hTERT and MUC-1 have been reported in these a few years. In addition, recent reports about the simultaneous presentation of peptides in both MHC class I and class II molecules on DCs after mRNA electroporation show another superiority of mRNA transfection into DCs. In this presentation, we demonstrate successful generation of tumor antigen specific CTLs using with DCs transfected with IVT mRNA such as SART-1 and WT-1 by electroporation. This is the first report about the generation of SART-1 and WT-1 specific CTLs by using mRNA transfected DCs. [Methods] HLA-A24 positive human PB CD14+ cell-derived DCs were transfected with IVT mRNA (SART-1and WT-1) by electroporation. MRNA transfected DCs were co-cultured with autologous lymphocytes. The bulk co-cultures were re-stimulated several times with same DCs. CD8+ cells were separated and CTL activity was evaluated by 51chromium release assay. To determine whether the induced CTL cells could recognize the target cells in an HLA class I restricted manner, anti-HLA class I monoclonal antibodies were utilized to block the cytotoxicity of effectors. [Results] Electroporation of mRNA showed no effect on the surface phenotypes and antigen presenting ability of DCs. In addition to the demonstration of efficient transfection of M1 mRNA into DCs by using RT-PCR, which eliminated the amplification of transfected mRNA by the treatment with RNase before RNA extraction from the transfected cells, we identified the definite expression of WT-1 protein in the cytoplasm of DCs by using immunoblotting. CTL assay indicated that 1) DCs transfected with mRNA stimulated the generation of antigen-specific CTLs which are capable of lysing autologous DCs transfected with the same mRNA. 2) CTLs also demonstrated cytotoxic ability against cell lines such as KE-4 presenting SART-1 peptides on HLA-A24, MEGO1 presenting WT-1 peptides on MHC class I, and HLA-A24 cDNA transfected T2 which were used as target cells after co- incubation with 9 mer SART-1 peptides with strong affinity to HLA-A24. 3) Each cytotoxicities were markedly blocked after co-incubation of target cells with anti-MHC class I antibody and not inhibited with anti-MHC class II antibody. [Conclusion] Our results showed that IVT mRNA-transfected DCs which is constructed non-virally have a highly efficient ability to stimulate specific T-cell immunity against tumor. Unlike peptide- or tumor cells extract-pulsed DCs based vaccines, anti-tumor immunotherapy using the DCs transfected with antigen mRNA could be extended to a wide range of patients who have previously been excluded from clinical trials for the reason of the un-identification of tumor specific antigens, for the reason of the impossibility of obtaining sufficient tumor specimens, or for the reason of MHC restriction of the tumor specific antigens.

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Self Antigens Expressed by Solid Tumors Do Not Efficiently Stimulate Naive or Activated T Cells: Implications for Immunotherapy

Journal of Experimental Medicine ◽

10.1084/jem.186.5.645 ◽

1997 ◽

Vol 186 (5) ◽

pp. 645-653 ◽

Cited By ~ 216

Author(s):

Daniel E. Speiser ◽

Renata Miranda ◽

Arsen Zakarian ◽

Martin F. Bachmann ◽

Kim McKall-Faienza ◽

...

Keyword(s):

Mhc Class I ◽

Tumor Antigen ◽

Simian Virus 40 ◽

T Antigen ◽

Class I ◽

Prolonged Survival ◽

Activated T Cells ◽

Ctl Response ◽

Insulin Promoter

Induction and maintenance of cytotoxic T lymphocyte (CTL) activity specific for a primary endogenous tumor was investigated in vivo. The simian virus 40 T antigen (Tag) expressed under the control of the rat insulin promoter (RIP) induced pancreatic β-cell tumors producing insulin, causing progressive hypoglycemia. As an endogenous tumor antigen, the lymphocytic choriomeningitis virus (LCMV) glycoprotein (GP) was introduced also under the control of the RIP. No significant spontaneous CTL activation against GP was observed. However, LCMV infection induced an antitumor CTL response which efficiently reduced the tumor mass, resulting in temporarily normalized blood glucose levels and prolonged survival of double transgenic RIP(GP × Tag2) mice (137 ± 18 d) as opposed to control RIP-Tag2 mice (88 ± 8 d). Surprisingly, the tumor-specific CTL response was not sustained despite the facts that the tumor cells continued to express MHC class I and LCMV-GP–specific CTLs were present and not tolerized. Subsequent adoptive transfer of virus activated spleen cells into RIP(GP × Tag2) mice further prolonged survival (168 ± 11 d), demonstrating continued expression of the LCMV-GP tumor antigen and MHC class I. The data show that the tumor did not spontaneously induce or maintain an activated CTL response, revealing a profound lack of immunogenicity in vivo. Therefore, repetitive immunizations are necessary for prolonged antitumor immunotherapy. In addition, the data suggest that the risk for induction of chronic autoimmune diseases is limited, which may encourage immunotherapy against antigens selectively but not exclusively expressed by the tumor.

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Identification of a unique tumor antigen as rejection antigen by molecular cloning and gene transfer.

Journal of Experimental Medicine ◽

10.1084/jem.164.5.1516 ◽

1986 ◽

Vol 164 (5) ◽

pp. 1516-1530 ◽

Cited By ~ 28

Author(s):

H J Stauss ◽

C Van Waes ◽

M A Fink ◽

B Starr ◽

H Schreiber

Keyword(s):

Mhc Class I ◽

Tumor Cell Line ◽

Tumor Rejection ◽

Class I ◽

Transplantation Antigen ◽

The Novel ◽

Gene Encoding ◽

Mhc Class I Molecule ◽

T Cell Clone ◽

I Gene

Tumor-specific transplantation antigens are antigens that can lead to complete immunological destruction of a transplanted cancer by the syngeneic host. When such antigens are expressed on cancers induced by chemical or physical carcinogens, then they are usually unique, i.e., antigenically different for each independently induced tumor. In this study, we show that the product of a gene encoding a novel MHC class I molecule and isolated from the murine UV light-induced regressor tumor 1591 represents one such unique tumor-specific transplantation antigen that causes tumor rejection. The major evidence comes from our finding that 1591 progressor variants regularly lost the gene encoding this antigen that is expressed in the parental tumor that regresses in normal mice; furthermore, reintroduction of this gene into a 1591 progressor variant by DNA transfection caused the progressor variant to regress in normal immunocompetent mice. Thus, the progressor tumor reverted to the parental regressor phenotype following transfection. Consistent with the conclusion that the expression of the novel MHC class I gene following transfection was responsible for the regressor phenotype is also our finding that a variant of the transfected tumor that had lost expression of the transfected gene resumed its progressive growth behavior. Finally, we show that the molecule encoded by the novel class I gene is specifically recognized by a syngeneic tumor-specific cytolytic T cell clone that we have previously shown to select in vitro for progressor variants from the parental regressor tumor cell line. It remains to be determined to what extent unique tumor-specific rejection antigens of other highly immunogenic regressor tumors are encoded by novel MHC class I genes and whether these genes represent germline mutations or somatic mutations caused by the carcinogen treatment.

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